Recently, in order to reduce air pollution caused by exhaust gases of vehicles, the vehicles are being manufactured based on studies for securing driving power by using an internal combustion engine and/or an electric motor. In this regard, the vehicles have been evolved in an order of a hybrid vehicle, a plug-in hybrid vehicle, and an electric vehicle. In this case, the hybrid vehicle and the plug-in hybrid vehicle include an internal combustion engine, an electric motor, and a battery pack, and the electric vehicle includes an electric motor and a battery pack without an internal combustion engine.
In addition, the battery pack has been evolved together with the hybrid vehicle, the plug-in hybrid vehicle, and the electric vehicle. The battery pack is configured to be chargeable outside and/or inside of the electric vehicle. The battery pack includes a cooling structure and a battery module, and the cooling structure surrounds the battery module. The battery module includes battery accommodation structures (for example, cartridges) that are sequentially stacked on each other, and battery cells between the battery accommodation structures. The battery cells externally generate heat via repeated charging and discharging. At this time, the cooling structure cools the battery cells via a heat exchange, by exchanging heat with the battery cells by using external air while the battery module is driven.
Accordingly, a shape of the cooling structure largely affects cooling effects of the battery cells per unit time. A lot of studies related to the shape of the cooling structure are being conducted. An example of the studies is KR 10-2014-0141825 (published on Dec. 11, 2014) entitled “Secondary Battery and Battery Module Having the Same”. The battery module includes elastic pads, battery cells, cover members, and frame members. The elastic pads have a ring shape and are sequentially stacked on each other in the battery module, and the battery cells are located between the elastic pads to expose sealing units through the elastic pads.
The cover members are located below and above the elastic pads to surround the elastic pads in a sandwich structure. The frame members have a shape of ‘[’, and accommodates the elastic pads, the battery cells, and the cover members by being located along edges of the battery cells and cover members. Here, the elastic pads and the cover members fix the battery cells inside the frame members, and the cover members cools the battery cells via a heat exchange, by exchanging heat with external air.
However, since the battery cells are surrounded by the elastic members, the cover members, and the frame members, heat of the battery cells are gradually accumulated between the elastic members, the cover members, and the frame members while the battery module is driven. The accumulated heat of the battery cells not only degrades electric characteristics of the battery cells, but also changes shapes of the elastic members, the cover members, and the frame members.